HTML5本地存储Localstorage

转载： 叶小钗

简单的 localstorage操作

<div id="msg" style="margin: 10px 0; border: 1px solid black; padding: 10px; width: 300px; height: 100px;"> </div> <input type="text" id="text" /> <select id="type"> <option value="session">sessionStorage</option> <option value="local">localStorage</option> </select> <button οnclick="save();"> 保存数据</button> <button οnclick="load();"> 读取数据</button> <script type="text/javascript"> var msg = document.getElementById('msg'), text = document.getElementById('text'), type = document.getElementById('type'); function save() { var str = text.value; var t = type.value; if (t == 'session') { sessionStorage.setItem('msg', str); } else { localStorage.setItem('msg', str); } } function load() { var t = type.value; if (t == 'session') { msg.innerHTML = sessionStorage.getItem('msg'); } else { msg.innerHTML = localStorage.getItem('msg'); } } </script>

真实情景

实际工作中对localstorage的使用一般有以下需求： 　　① 缓存一般信息，如搜索页的出发城市，达到城市，非实时定位信息 　　② 缓存城市列表数据，这个数据往往比较大 　　③ 每条缓存信息需要可追踪，比如服务器通知城市数据更新，这个时候在最近一次访问的时候要自动设置过期 　　④ 每条信息具有过期日期状态，在过期外时间需要由服务器拉取数据 　　⑤ ......

define([], function () {     var Storage = _.inherit({     //默认属性     propertys: function () {         //代理对象，默认为localstorage       this.sProxy = window.localStorage;         //60 * 60 * 24 * 30 * 1000 ms ==30天       this.defaultLifeTime = 2592000000;         //本地缓存用以存放所有localstorage键值与过期日期的映射       this.keyCache = 'SYSTEM_KEY_TIMEOUT_MAP';         //当缓存容量已满，每次删除的缓存数       this.removeNum = 5;       },       assert: function () {       if (this.sProxy === null) {         throw 'not override sProxy property';       }     },       initialize: function (opts) {       this.propertys();       this.assert();     },       /*     新增localstorage     数据格式包括唯一键值，json字符串，过期日期，存入日期     sign 为格式化后的请求参数，用于同一请求不同参数时候返回新数据，比如列表为北京的城市，后切换为上海，会判断tag不同而更新缓存数据，tag相当于签名     每一键值只会缓存一条信息     */     set: function (key, value, timeout, sign) {       var _d = new Date();       //存入日期       var indate = _d.getTime();         //最终保存的数据       var entity = null;         if (!timeout) {         _d.setTime(_d.getTime() + this.defaultLifeTime);         timeout = _d.getTime();       }         //       this.setKeyCache(key, timeout);       entity = this.buildStorageObj(value, indate, timeout, sign);         try {         this.sProxy.setItem(key, JSON.stringify(entity));         return true;       } catch (e) {         //localstorage写满时,全清掉         if (e.name == 'QuotaExceededError') {           //            this.sProxy.clear();           //localstorage写满时，选择离过期时间最近的数据删除，这样也会有些影响，但是感觉比全清除好些，如果缓存过多，此过程比较耗时，100ms以内           if (!this.removeLastCache()) throw '本次数据存储量过大';           this.set(key, value, timeout, sign);         }         console && console.log(e);       }       return false;     },       //删除过期缓存     removeOverdueCache: function () {       var tmpObj = null, i, len;         var now = new Date().getTime();       //取出键值对       var cacheStr = this.sProxy.getItem(this.keyCache);       var cacheMap = [];       var newMap = [];       if (!cacheStr) {         return;       }         cacheMap = JSON.parse(cacheStr);         for (i = 0, len = cacheMap.length; i < len; i++) {         tmpObj = cacheMap[i];         if (tmpObj.timeout < now) {           this.sProxy.removeItem(tmpObj.key);         } else {           newMap.push(tmpObj);         }       }       this.sProxy.setItem(this.keyCache, JSON.stringify(newMap));       },       removeLastCache: function () {       var i, len;       var num = this.removeNum || 5;         //取出键值对       var cacheStr = this.sProxy.getItem(this.keyCache);       var cacheMap = [];       var delMap = [];         //说明本次存储过大       if (!cacheStr) return false;         cacheMap.sort(function (a, b) {         return a.timeout - b.timeout;       });         //删除了哪些数据       delMap = cacheMap.splice(0, num);       for (i = 0, len = delMap.length; i < len; i++) {         this.sProxy.removeItem(delMap[i].key);       }         this.sProxy.setItem(this.keyCache, JSON.stringify(cacheMap));       return true;     },       setKeyCache: function (key, timeout) {       if (!key || !timeout || timeout < new Date().getTime()) return;       var i, len, tmpObj;         //获取当前已经缓存的键值字符串       var oldstr = this.sProxy.getItem(this.keyCache);       var oldMap = [];       //当前key是否已经存在       var flag = false;       var obj = {};       obj.key = key;       obj.timeout = timeout;         if (oldstr) {         oldMap = JSON.parse(oldstr);         if (!_.isArray(oldMap)) oldMap = [];       }         for (i = 0, len = oldMap.length; i < len; i++) {         tmpObj = oldMap[i];         if (tmpObj.key == key) {           oldMap[i] = obj;           flag = true;           break;         }       }       if (!flag) oldMap.push(obj);       //最后将新数组放到缓存中       this.sProxy.setItem(this.keyCache, JSON.stringify(oldMap));       },       buildStorageObj: function (value, indate, timeout, sign) {       var obj = {         value: value,         timeout: timeout,         sign: sign,         indate: indate       };       return obj;     },       get: function (key, sign) {       var result, now = new Date().getTime();       try {         result = this.sProxy.getItem(key);         if (!result) return null;         result = JSON.parse(result);           //数据过期         if (result.timeout < now) return null;           //需要验证签名         if (sign) {           if (sign === result.sign)             return result.value;           return null;         } else {           return result.value;         }         } catch (e) {         console && console.log(e);       }       return null;     },       //获取签名     getSign: function (key) {       var result, sign = null;       try {         result = this.sProxy.getItem(key);         if (result) {           result = JSON.parse(result);           sign = result && result.sign         }       } catch (e) {         console && console.log(e);       }       return sign;     },       remove: function (key) {       return this.sProxy.removeItem(key);     },       clear: function () {       this.sProxy.clear();     }   });     Storage.getInstance = function () {     if (this.instance) {       return this.instance;     } else {       return this.instance = new this();     }   };     return Storage;   }); 这段代码包含了localstorage的基本操作，并且对以上问题做了处理，而真实的使用还要再抽象：

define(['AbstractStorage'], function (AbstractStorage) {     var Store = _.inherit({     //默认属性     propertys: function () {         //每个对象一定要具有存储键，并且不能重复       this.key = null;         //默认一条数据的生命周期，S为秒，M为分，D为天       this.lifeTime = '30M';         //默认返回数据       //      this.defaultData = null;         //代理对象，localstorage对象       this.sProxy = new AbstractStorage();       },       setOption: function (options) {       _.extend(this, options);     },       assert: function () {       if (this.key === null) {         throw 'not override key property';       }       if (this.sProxy === null) {         throw 'not override sProxy property';       }     },       initialize: function (opts) {       this.propertys();       this.setOption(opts);       this.assert();     },       _getLifeTime: function () {       var timeout = 0;       var str = this.lifeTime;       var unit = str.charAt(str.length - 1);       var num = str.substring(0, str.length - 1);       var Map = {         D: 86400,         H: 3600,         M: 60,         S: 1       };       if (typeof unit == 'string') {         unit = unit.toUpperCase();       }       timeout = num;       if (unit) timeout = Map[unit];         //单位为毫秒       return num * timeout * 1000 ;     },       //缓存数据     set: function (value, sign) {       //获取过期时间       var timeout = new Date();       timeout.setTime(timeout.getTime() + this._getLifeTime());       this.sProxy.set(this.key, value, timeout.getTime(), sign);     },       //设置单个属性     setAttr: function (name, value, sign) {       var key, obj;       if (_.isObject(name)) {         for (key in name) {           if (name.hasOwnProperty(key)) this.setAttr(k, name[k], value);         }         return;       }         if (!sign) sign = this.getSign();         //获取当前对象       obj = this.get(sign) || {};       if (!obj) return;       obj[name] = value;       this.set(obj, sign);       },       getSign: function () {       return this.sProxy.getSign(this.key);     },       remove: function () {       this.sProxy.remove(this.key);     },       removeAttr: function (attrName) {       var obj = this.get() || {};       if (obj[attrName]) {         delete obj[attrName];       }       this.set(obj);     },       get: function (sign) {       var result = [], isEmpty = true, a;       var obj = this.sProxy.get(this.key, sign);       var type = typeof obj;       var o = { 'string': true, 'number': true, 'boolean': true };       if (o[type]) return obj;         if (_.isArray(obj)) {         for (var i = 0, len = obj.length; i < len; i++) {           result[i] = obj[i];         }       } else if (_.isObject(obj)) {         result = obj;       }         for (a in result) {         isEmpty = false;         break;       }       return !isEmpty ? result : null;     },       getAttr: function (attrName, tag) {       var obj = this.get(tag);       var attrVal = null;       if (obj) {         attrVal = obj[attrName];       }       return attrVal;     }     });     Store.getInstance = function () {     if (this.instance) {       return this.instance;     } else {       return this.instance = new this();     }   };     return Store; });